1. Field of the Invention
The present invention relates to archery bow assemblies, and more particularly, to an actuating system for dynamically reducing the draw weight of a bow and damping extraneous motions of the bow following a shot.
2. Description of the Related Art
Archery bows typically include a riser defining a handle for holding the bow and a pair of flexible limbs extending from opposite ends of the riser to distal ends. A wheel or cam is commonly rotatably attached to the distal end of each limb and a bowstring and harness system is wound between the wheels or cams of the limbs. The limbs are typically flexible such that as a bow is drawn, potential energy is typically stored within the limbs themselves. When the bowstring is released, the potential energy is converted to kinetic energy for propelling the arrow as the limbs return to a rest position.
The bowstring and harness system is loaded under high tension, thereby defining a draw weight as the force required to pull the bowstring to its full position. It is common to connect the limbs of the bow to the riser with a connector which extends through the limb and is threaded into the riser. As the bow is drawn, the limbs flex and exert a significant shearing force, typically on the connector. The force imparted to an arrow upon release of the bowstring, or the bow thrust, is directly proportional to the draw weight. While it is desirable to provide an increased bow thrust for propelling the arrow with increased speed and force, the corresponding increase in the draw weight will increase the shearing force on the connector and vibration in the bow. Therefore, it is desirable to provide a bow actuating system which maximizes the bow thrust while decreasing the draw weight by supporting at least some of the force exerted by the limbs.
The draw weight of the bow is typically changed by attaching a different length string between the wheels or cams, by changing the size of the limbs, or by changing the angle or orientation of the limbs relative to the riser. The connector may be loosened to change the orientation of the limbs relative to the riser and slightly adjust the draw weight of the bow. However, prior art systems providing orientation adjustment by loosening the connector require manual adjustment, which can only occur when the bow is not is use. Thus, it is also desirable to provide a bow actuating system which dynamically changes the orientation of the limbs during use of the bow to minimize the draw weight.
The accuracy of an archery bow largely depends on elimination of extraneous motions of the bow. As the bowstring is released, the riser and the limbs vibrate causing the bowstring to oscillate as the arrow leaves the bow. The oscillation affects the trajectory of the arrow, greatly impacting an archer""s accuracy, while also causing unwanted noise and hand shock. Therefore, it is further desirable to provide a bow actuating system which acts as a shock absorber after a shot, thereby reducing vibration of the bow.
Accordingly, the invention provides an archery bow comprising a riser extending between opposing first and second ends. A limb is coupled to each end of the riser. Each limb has a first end for connecting to the riser and a second distal end. An axle pivotally connects at least one of the limbs to one end of the riser. An actuator is operatively coupled between at least one of the limbs and the riser adjacent the axle for supporting the limbs about the riser, and thus for supporting the forces exerted by the limb. The actuator includes a resilient member for storing energy as the bow is drawn, and releasing energy as the bow is released. The resilient member is pivotally attached to both the riser and the limb, elongating or compressing to dynamically change the angle between the riser and the limb while the bow is in use to minimize the draw weight. Because of the three-pivot system, the force exerted by the limbs impacts the actuator at approximately a 90 degree angle throughout the shot, thereby maximizing bow thrust. After the shot, the resilient member acts as a shock absorber to reduce the vibration of the bow.